- Location
- Derry/Londonderry, County Londonderry
- Main postcode district
- BT48
- Nearby (straight line)
- Limavady (15 miles), Coleraine (27 miles) and Omagh (28 miles)
- Survey and quote
- Free, with a fixed written quote
Dock traffic lights are red and green signals mounted outside and inside a loading bay to tell the driver and dock staff when it is safe to move or load. Interlocks are control links that stop equipment operating out of sequence, for example preventing the door opening until the trailer is restrained, or the leveller operating until the door is fully open.
How does this suit sites in Derry/Londonderry?
Whether your unit in Derry/Londonderry has one dock or twenty, the survey looks at each bay's existing controls before we quote a fixed price in writing. Distribution centres near Derry/Londonderry taking trailers from many different hauliers benefit from a signal every driver understands, regardless of language or familiarity with the site.
Food and chilled operations around Derry/Londonderry with inflatable shelters often add interlocks so the shelter only inflates once a trailer is docked and restrained.
Step one is a survey at your site in Derry/Londonderry, which costs nothing and carries no obligation. Step two is a written quote with a fixed price and a clear scope. Step three is installation, scheduled around your operation and carried out by specialist installation engineers working under our management, including evenings or weekends if agreed. Step four is handover, when the equipment is tested in front of you and the paperwork is passed over.
Which interlocks should a loading bay have?
The most useful loading bay interlocks stop the door opening until the trailer is in place or restrained, and stop the leveller operating until the door is fully open. Beyond that, the right set depends on the equipment fitted and your risk assessment.
- Door to restraint: the door cannot open until the restraint is engaged or a trailer is detected.
- Leveller to door: the leveller cannot be raised until the door is fully open, which prevents the lip hitting door panels.
- Door to leveller: the door cannot close until the leveller is back in its parked position.
- Restraint release: the restraint only releases once the door is closed and the leveller parked.
- Shelter to trailer: an inflatable shelter only inflates when a trailer is docked.
On a bay without a restraint, a trailer presence sensor can take its place in the door logic, although it confirms a trailer is there rather than holding it. Combining interlocks with vehicle restraints gives the strongest protection against drive-away.
How do inside and outside dock traffic lights work together?
Inside and outside dock lights always show opposite colours: when the driver sees red, dock staff see green, and the other way round. Each light is aimed at a different person, so each one only ever gives one instruction.
- Outside light, facing the driver: red means stay on the bay because loading is in progress; green means the bay is clear to leave or to reverse on to.
- Inside light, facing dock staff: green means the trailer is in place and it is safe to open the door and load; red means do not open the door or enter the trailer.
Lights can be switched in three main ways:
- Manually, by a switch beside the door, relying on dock staff to change it at the right moment.
- By door position, so opening the door automatically turns the outside light red.
- By the restraint, so the light only changes when the trailer is physically held.
The same published guide range applies across Northern Ireland; access, out-of-hours working and site conditions are confirmed at the free survey.
What we look at on site
- Temperature requirements for chilled, frozen or ambient goods
- Drainage on recessed or sloping dock approaches
- Condition of any existing leveller pit, kerb angles and pit drainage
- Gaps around trailers where heated or chilled air escapes
- Bumper position and wear or damage on the dock face
- Clear opening width and height for each door
Options to discuss
Trailer presence sensors
Sensors that detect a trailer on the bay, used to switch lights, enable the door or trigger an inflatable shelter where no restraint is fitted.
Restraint interlock package
Door, lights and vehicle restraint tied together so the door only opens once the trailer is held and the restraint only releases when loading is finished.
Planning, building control and safety law in Northern Ireland
Northern Ireland has its own system. Structural alterations at a site in Derry/Londonderry, such as a new opening or dock pit, may need building control approval from the council, and external structures such as loading houses or canopies can need planning permission through the council planning service. We check what applies at survey.
Questions about dock traffic lights and interlocks in Derry/Londonderry
What details do you need from us to quote for dock traffic lights and interlocks?
To get started, send the site address in Derry/Londonderry, the number of bays or openings, approximate sizes, and photos of the dock from inside and outside. Tell us what vehicles you load, what goods you handle and any temperature requirements. Drawings help on new builds. We then arrange the free survey and confirm the details before the written quote is issued.
Can you work outside our normal operating hours in Derry/Londonderry?
Yes, by arrangement. Evening, night and weekend working can be planned so the installation causes as little disruption as possible to your loading schedule. Out-of-hours work can affect the price, so mention it at the survey and we will include it in the written quote. The agreed times are confirmed in the programme before the job starts.
Do you cover Derry/Londonderry for dock traffic lights and interlocks?
Yes. We take on dock traffic lights and interlocks for businesses in Derry/Londonderry and across County Londonderry. We survey the site, provide a fixed written quote and manage the installation, with specialist installation engineers working under our management. Visits are arranged in advance at a time that suits your operation, and the same single contact stays with the job through to handover.
Do traffic lights and interlocks need maintenance?
Yes. Lights, sensors and interlocks should be checked at each planned service visit, including testing the full sequence and confirming that steps attempted out of order are blocked. As part of the dock equipment they fall under PUWER, which requires work equipment to be maintained in a safe condition.
Which way round do the inside and outside lights work?
The inside and outside lights always show opposite colours. While a trailer is being loaded, the outside light is red so the driver stays put and the inside light is green so staff can work. When loading is finished and the door is closed, the inside light turns red and the outside light turns green for the driver.
Dock traffic lights and interlocks near Derry/Londonderry
If your site is not in Derry/Londonderry itself, it may be near one of these: Limavady (15 miles), Coleraine (27 miles) and Omagh (28 miles). Pick the closest.
Other loading bay services in Derry/Londonderry
Full guide to dock traffic lights and interlocks · Everything we do in Derry/Londonderry
Phone us to discuss your loading bay in Derry/Londonderry, or start with the online quote tool if you prefer to send details first.